This invention relates to fault protection arrangements for electric power distribution systems.
The protection of personnel and electric system components, such as generators, motors, cables and power conversion equipment from short circuit conditions and other system anomalies is essential for safe and reliable distribution of electric power. Power continuity may also be critical for vital loads within a system. Heretofore, hierarchical protective arrangements using mechanical circuit breakers and fuses have been designed to utilize downstream protective devices which open first in order to clear a fault in a downstream circuit segment. In such systems the response times are slow and many protective devices are required. Moreover, time coordination of protective devices is necessary and, where fuses are used, blown fuses must be replaced before the system is completely restored.